Electromagnetic relay structure



Aug 31, 1965 w. D. MAYNARD 3,204,061

ELECTROMAGNETIC RELAY STRUCTURE Filed Nov. 28, 1962 4 Sheets-Sheet 1 ,es|O eo 54 se l 5on i 5| 59 9 l 55 22-6 87 76 t 46 65 if 42 82 83 F f? 3524 .f --1 85 n d =4 3 23g 64 22 25 34 93 9| I! 2 3e 38 94 4 @i 43 90 7086 es I7 46 6| wvl l V59' mi 59' 72 V u V V |65 59 97 eo 54 l5 50 53 ,4FIG. 3.

FISI. 2 62 IN VEN TOR.

Y WDMAYNARD Bww HIS ATTORNEY Aug. 31, 1965 w. D. MAYNARD ELECTROMAGNETICRELAY STRUCTURE 4 Sheets-Sheet 2 FIG. 6.

Filed Nov. 28, 1962 FIG. 5.

FIGB.

FIG. 7.

INVENTOR. W. D. MAY NA R D HIS ATTORNEY FIGS.

4 Sheets-Sheet 3 Filed NOV. 28, 1962 FIG.|3.

CLOSED AIR GAP OPEN AIR GAP H(NI) FIG. IO.

INVENToR. W. D. M AY N A R D HIS ATTORNEY Aug. 31, 1965 w. D. MAYNARDELECTROMAGNETIC RELAY STRUCTURE 4 Sheets-Sheet 4 Filed Nov. 28, 1962 FIG. I5.

DEFLECTION TRAVEL BACK 'OBARMATURE CONTACTS FULLY OPEN RELEASED I |00FRONT CONTACTS CLOSE ARMATURE FULLY PICKED UP RD n mon m MA f O WN n IVI.A A Q|u M H D Y? B E M me l R a wu oc GM OO RL PS NN EE OO ER Lm ANAH ll @UT C um ||r| EC I\||\ Vl SA PO TAR LF mp0 G .II-3 Cl Nmw wRA E2 GT4United States Patent O 3,204,061 ELECTROMAGNETIC RELAY STRUCTURE WheelerD. Maynard, Meudon, N.Y., assignor to General Signal Corporation, acorporation of New York Filed Nov. 28, 1962, Ser. No. 240,637 13 Claims.(Cl. 200--104) This application is a continuation-in-part of myapplication Serial Number 142,391 liled October 2, 1961, now abandoned.

The present invention relates to relays, and more particularly to anelectromagnetic relayy having improved structural and operatingfeatures. In one specific aspect, the present invention relates to animproved relay assembly of the type in which a multiplicity of movablecontact blades are operated by the armature through the medium lof aninsulative card.

Heretofore, electromagnetic relays, particularly those having theoperating characteristics, reliability, and durability sutlicient foruse in railway signaling or code communication systems for example,required a number of machined parts, considerable skill in theirassembly, and intricate post-assembly adjustment. The most common ofthese adjustments after assembly, for example, were to the armaturebiasing means to insure proper loading pressures, to the relay Contactblades for insuring proper alignment and the desired contact travel andloading pressure, and adjustment to the residual, working and hinge airgaps of the armature to obtain proper armature travel for the desiredoperation.

ln present day complex communication or switching systems, relayrequirements have become more rigid. For example, the relays must berelatively small and compact, be able to control a multiplicity ofcircuits, be versatile in their operation, be able to be mounted inclose relation with one another, have rapid operating characteristicsfor required applications, should be so constituted that they can switchsolid state devices reliably, and also maintain their reliability inoperation for long periods of time.

The purpose of the present invention is to provide an improved relaywhich does not require any post assembly adjustment, is easily andrapidly assembled from parts that can be mass produced, is able to meetthe requirements necessary for exacting applications, and which remainsreliable in its operation for long periods of time.

In furtherance thereof, one of the objects of the present invention isto provide an improved relay that is so constructed that its separatecomponent parts are so configurated to be capable of being assembledwithout skill in precise and proper relationship, with each part havingmeans for precisely registering with another to provide a compactunitary structure, the operating characteristics of which areinsensitive to minor production variations.

Another object of this invention is to provide an improved relay whereinthe armature loading pressure during operation is relatively uniformthroughout each predetermined portion of armature travel.

Another object of this invention is to provide an improved relay whereinthe contact pressure is relatively uniform throughout their entirelimits of travel.

Another object of this invention is to provide an improved relayassembly Which eliminates the need for adjusting the air gap and travelof the armature.

Another object of this invention is to provide an improved relayassembly whereby the various contact blades can be atiixedly andretainedly positioned in proper and precise alignment in theirrespective individual insulating mounts with zero tolerance and toremain in such precise position, not only when completely assembled, butwhen the individual mounts are being handled during assembly.

A further object of this invention is to provide an improved relayhaving operating characteristics capable of operating solid statedevices reliably.

A further object of this invention is to provide an improved relayassembly having built-in arc suppression means.

A still further object of this invention is to provide an improved relaywherein the relative positioning of all of the movable components of therelay is precisely fixed by virtue of features inherent in thestructural make-up of the relay.

A still further object of this invention is to provide an improvedassembly and means for allixedly attaching the insulative card that iscarried by the armature, to operate the contact blades.

A still further object of this invention is to provide an improved relayassembly which permits the relay to be used in varied applications, andis made up of cornponents that are either molded or stamped and requireno machining.

Other objects of this invention will become apparent from thespecification, the drawings, and the appended claims.

In the drawings:

FIG. 1 is a front View of a relay according to the present inventionwith parts cut away to show various structural features of the relaywhen assembled;

FIG. 2 is a sectional view of the relay taken along line 2-2 of FIG. 1and viewed in the direction of the arrows;

FIG. 3 is a sectional view of the relay taken along line 3--3 of FIG. land viewed in the direction of the arrows;

FIG. 4 is a fragmentary sectional View taken along line 4-4 of FIG. 3and viewed in the direction of the arrows to illustrate how the relayarmature is operatively connected to the relay core;

FIG. S is a rear view of the relay;

FIG. 6 is a fragmentary sectional View taken along line 6 6 of FIG. 5and viewed in the direction of the arrows to illustrate the arcsuppression means provided in the relay;

FIG. 7 is a fragmentary sectional view taken along line 7-7 of FIG. 5and viewed in the direction of the arrows to illustrate the mounting ofthe individual relay contact blades adjacent the rear end of the relay;

FIG. 8 is a fragmentary sectional view taken along line S-8 of FIG. 5and viewed in the direction of the arrows to illustrate the mounting ofthe terminal plates for the relay coils;

FIG. 9 is an enlarged isometric view of one of the mounting membersemploy-ed in the relay to show its configuration for holding the contactblades in proper aligned position for assembly and illustratingfragmentarily one Contact blade in such position;

FIG. 10 is a fragmentary front view showing one modified arrangement forspring biasing the stationary contact blades toward their releasedposition;

FIG. 1l is a cross-sectional fragmentary view of a further modilicationfor spring biasing the stationary contact blades toward their releasedpositions;

FIG. 12 is a fragmentary sectional view of a still further modiiicationspring biasing means for a contact blade assembly;

FIG. 13 is `a graph illustrating the operating characteristics of arelay constructed in accordance with the present invention;

FIG, 14 is a graphical illustration of typical load and pull curves fora relay constructed -in accordance with one embodiment of lthe presentinvention;

FIG. l5 is a graph .illust-rating the relationship between the force anddeformation of an elastic body; and

FIG. 16 illu-strates a general form -of external energizing circuit forthe relay embodying the present invention.

seo/toer Generally speaking, and without attempting to limit the scopeott the present invention, the relay is comprised ot an elongate core ofrectangular cross-section having a pair of coil structures positionedintermediate the ends thereof. An armature, also of substantiallyrectangular cross-section, is opena-brly connected to the core byinserting one end of the armature through an enlarged portion of anirregularly .shaped opening provided adjacent one end of the core. Thearmature Iis retained in such position by a pair of mating pilas-ticblocks which `are so formed lto embrace intimately the upper and lowerfaces of t-he core adjacent one end thereof a portion of one blockextending into the irregular opening of lthe core. One of the matinglplastic members and the ar-mature has a portion for retaining a `springto hold resiliently the armature against those edges of the portion ofthe irregular opening of the core on which it is adapted to pivot duringoperation. This `assembly precisely positions the armature without thenecessity of adjusting the hinge air gap.

A Iplurality of molded plastic insulating members or 'wafers are socongurated to be stacked in intimate relationship on the upper and lowerfaces of the pair of mated blocks Iwith eac-h insulating member holdingin precise alignment a plurality of elongate metallic contact blades.Thus, when the .fixed end of the rel-ay is completely assembled, theelongate metallic contact blades extend longitudinally of the core inspaced relation ,from both the upper and lower lfaces thereof.

Each of the plastic insulating members has a plurality of shallowrecesses or grooves for receiving the xed ends of the contact blades.Each contact bdade is hel-d in precise alignment in its respective slotor recess by a resilient member 4integral with the insulating Wafer lforassembly. In :use the alignment is maintained against external forcessuch as handling and curve strain by sharp projections or chisel pointswhich embed into the contiguous surface of the wafer. One of the matedblocks is also provided with a pair `ot circular recesses to receive anon-linear resistive element which electrically connects to the terminalplates of the energizable coils to provide a -means `for suppressing thearcing of the contacts utilized to energize and deenergize Ithe relay.

The stacked insulating members and the mated blocks are fastenedpermanently to the core in assembled position by a `set of elongatestuds which extend through aligned holes in each individual member landwhich are riveted at one end. Once the rivets are set, the assembly ofthe fixed end, or rear portion of the relay is completed.

The working end or forward portion of the relay is comprised of anintegrally formed molded frame having generally rectangular externalcontiguration similar to that of the stacked assembly at the rear end orr'ixed end of the relay. This `frame has `a plurality of spacedpartitions to form grate-like openings and a single larger centralopening which is generally rectangular but has shoulders and raisedsurfaces on the side walls. The trame is positioned through the `centralopening adjacent the front end of the core accurately by the yshoulderson the sidewall of the opening cooperating with the core. This frame is:fastened thereto by `the force of an arcuate spring member that isIwedged between opposing surfaces of the core and the walls of the largecentral opening. When in this position the free ends of the contactblades each extend .through one of the grate-like openings of the frame.The released position of the armature is determined by the internalsurface of the walls ot the larger central opening. A coil springengages the armature and the opposite wall of the central opening tobias the armature to this released position.

In the illustrated embodiment of the invention there are two closelyspaced horizontal rows ot so-called xed contact blades above the core,and two closely spaced horizontal rows of so-called rixed contactbla-des below the core. yEach contact blade of one row is aligned with acor-responding contact blade of the other row to constitute `front andback contacts respectively. Spring means are mounted in the frame tobias each fixed contact blade in engagement 'with the .adjacent surfaceof the Wall of the opening through which the Contact blade extends.Extending through an opening interposed between each of the iront andback contact blades is a movable contact blade for engaging a lfront orback Contact `selectively in response to the operation of the relay.

A plastic card having a plural-ity of horizontally extending slits,arranged in rows and columns, each of which is positioned to receive aprojection of a movable contact blade, is provided with a centralrectangular opening for mounting on the t'ree end of the armature. Theplastic card has an integrally formed finger that projects resilientlyinto the central opening and which lits in a hole in the end of thearmature when the .card is positioned on the armature. The projectionsof the movable contact blades are locked in position in .the slits. Theprojections on the contact blades are so formed that the card is lockedin operative position by `shifting it slightly to one side. The plasticcard iixes the position of the movable contact blades relative to thearmature so that when the `armature is in its released position thecontact elements on the movable Contact blades, engage contact elementson the back contact bla-des to cause each of them to be lifted slightlyfrom the wall or edge of its opening against the fonce of the springmeans positioned in the Iframe. When .the armature is picked up, themovable contact arms disengage the back contacts to permit them toengage the wall of their respective openings through the pressure of thesprings, and the contact elements on .the movable contact blades engageand lift the `front contact blades trom the wall or edge of its openingagainst the torce of the Ispring means.

ln accordance with the present invention, the individual spring means inthe 'frame lare `so constituted that they are deflected suflicientlyw-hen positioned in the openings to provide the proper contact pressurewhen the movable contact blades are in engagement with the trent or backcontacts depending upon the position of the armature. This pressure,which is termed armature loading pressure is further able to be moreaccurate and provide greater stability to the so-called fixed contactblades because of the position of each of the spring means relative toeach other and their position ot alignment with the air gap of the relay`close to the working ends of the contact blades. Thus, the contactblades are merely hinges and the flexibility factor inherent in thecontact blades themselves is reduced to an absolute minimum.

The .spring means also are so fonmed that they have relatively lowspring constants, that is, constants of proportionality which relate the`force exerted by the springs to the amount o-f spring deflection. Inbrief, they are lso-called low rate `spring means. Because the amount ofspring deflection, during relay operation, is small compared to theamount .the springs are deected when in assembled position, the exertedspring pressure varies minimally during relay loperation from the valuespreset when inserted. This prolongs the life of the relay, because awearing of the contact elements on the blades after continued operationdoes not appreciably affect the contact and armature loading pressure.These desired armature loading and contact pressures are accuratelydetermined by the cooperation of the springs in their compressedcondition with the inner face of the plastic molded .structure betweenwhich they are compressed.

'The residual air gap of the relay, that is, that which exists when therelay armature is in 'its energized `or picked up position is accuratelydetermined by covering that portion of the surface of the armature thatis in registry with the magnetic air gap with a thin accuratelydimensioned layer of nonrnagnetic material. This elimi- S hatesnecessity for adjusting this air lgap by means of pins or the like.

-Referring in detail to FIGS l through 9 by numerals of reference, therelay is comprise-d of a core 10, which may be stamped out fromappropriate rllat stock. The stamped core is an elongate metallic barsubstantially rectangular in configuration and cross section, which hasan irregularly coniigurated opening 1'1 adjacent its right- :hand endand a U-shaped recess |12 at its left-hand end, as viewed in FIG. 3.Centrally disposed on the core 10 are a pai-r of spools 14 which have :agenerally rectangular central opening for slidably receiving the core10. An energizing coil 15 is wound on each :off the spools 1'4. Anelongate armature that is generally referred to at 16, is substantiallyrectangular in cross-section and is bent to have a :substantiallyL-shaped configuration, with its short leg '17 at the right-hand end, asviewed in FIG. 2, and its longer leg having an off-set rportionIS at thelefthand end thereof. The armature .16 may be stamped out and formedsimultaneously with a progressive die. The right-hand leg 11:7 of theamature 16 has a pair of inwardly extending notches or recesses 1-9 atopposite side edges (IF'IG. 4), which notches are slightly wider thanthe thickness oif the core |10. In assembling the armature 16 inoperative position, .the short leg 17 is inserted through the irregularopening .1K1 at its enlarged portion which is defined by side wallportions 20 (FIG. 3), land then shifted to the left as viewed in FIGS..2 and 3 so that shoulders 21 of the core 10 engage in .the notches 19of .the armature leg 17, and surface portion 212 of the armature leg y17rabuts against tforward wall 23 of the core opening 1-1 which wall orside edge extends trans- Iverse .of the axis of the core 10.

With the wound spools 14 and the armature 16 so posi-tioned on the core10, a molded block 24, of insulating material, is positioned on the coreI10 in registry with the opening 111. This molded block 24 and the otherinsulative members hereinafter mentioned lare preferably a plastichaving a high melting point land low expansion characteristics, such asa polycarbonate resin, which may Ibe formed by injection molding. Theblock 24 has an irregularly shaped integrally formed projection 25, the

`configuration of which substantially corresponds to the irregularopening `111 `of the core I10, and is best illust-rated in FIG. 3. Theprojection 25 extends Ithrough the irregulanly shaped opening .11 of thecore 10 rearwardly of the armature 16, with its side faces adjacent theside wall portions 20 and 29 of the opening 111 in the core. Front faces`2.6 of the .projection 25 loosely contines the armature 1:6 in itsmounted position on the shoulders 21 of the core '10. The plastic lblock24 `also has integrally lformed tubular projections 27 that fit intoholes 28 of the core .10 to properly position it on the core. A spring30 is compressed in a chamber 31, rwhich chamber is formed by .a forwardwall 32 lon the projection 25 of the block y24 :and the rear surface ofthe short leg 17 of the armature k16 so that the axis of the spring 30is substantially in registry with .the uppermost portion of thetransverse side wall 213 of the core opening 1'1. A spring seat 33 whichfits in `a square cavity in the armature leg 17 and Ian appropriateproject-ion (not shown) on the wall 32 retains the spring 30 inposition. The force of the spring 30 resiliently biases the armature inits proper hinged or `pivotal position against the forward edge 2'3 ofthe irregularly shaped opening 111 to engage the `shoulders 21 of .thecore `10. This assembly renders unnecessary any adjustment of the hingeair gap.

A square headed mounting bolt 134 is positioned with its head in `arecess 35, .the forward waill of which is rear 'face 32 of theprojection 25 of the molded block 24 so that its shank extendsrearwardly through the rear narrow -channel of the irregular opening 11of .the core 10. A sleeve 36 may be inserted in the cavity 35 to bettersecure the holt 134 against movement and rotation.

Another molded block 38 of insulating material which is of similaroverall length and width to .the .plastic block 24 is positioned againstthe under plane surface of the core 10 as viewed in the drawings. Thisblock 38 has a shallow recess similar to the ycross-sectionalconfiguration of the projection 25 of the block 24 and tubularprojections similar to those referred to at y27 for block 24 so thatwhen the block 38 is pressed -against the under surface of the core '10,it mates with .the block 24 as viewed in FIGS. 2 and 5.

The block 24 has a pair of arcuate recesses 40 formed in its uppersurface to receive discs of material 41, such as Thyrite, for example,which has the property of providing high resistance to low operatingvoltage values, while providing low resistance to surge voltages. Thediscs 41, when seated in the recesses 40, are substantially flush withthe upper surface of the block 24 as viewed in FIG. 6. The upper surfaceof the block 24 and the lower surface of the block 38 are provided withirregularly shaped shallow recesses into which correspondinglyconfigurated terminal plates 42 (FIG. 8) and terminal plates 43 seat.Each of the terminal plates 42 and 43, which may be stamped from sheetcopper has a laterally projecting ear 44 to which a connector 45 of thewindings 15 is attached. Each of the terminal plates 42 and 43 also hasa rearwardly extending projection 46 for connection to an externalsource of energy for energizing the windings 15. Thus, the terminalsf-or energizing each of the windings 14 includes a terminal plate 42 anda terminal plate 43.

The projection 25 of the molded block 24 also has a pair of cylindricalbores, each of which communicates at the upper end with a respectiverecess 40 and at its lower end with the lower surface of the block 24 inregistry with a bore extending through the block 38 to form an elongatebore 47 (FIG. 6) when the blocks 24 and 38 are in mounted position onthe right-hand end of the core 10. A spring 48 is inserted in the longcylindrical bore 47 and is slightly compressed to be in good contactwith the disc 41 and a respective terminal plate 43 positioned on thelower surface of the block 38. The spring 4S also urges each disc 41 ingood contact with its respective terminal plate 42. Thus, the energizingcircuit for each of the windings 15 is electrically shunted by a paththat extends from a terminal plate 42, disc 41, spring 48, and aterminal 43. During operation, this assembly, which is built-in at thexed end of the relay, prevents excessive arcing at contacts such asthose illustrated, by way of example, in the general external energizingcircuit shown in FIG. 16 that are used to control energization anddeenergization of the relay windings 15.

A plurality of plastic members or wafers 50, which are rectangular inconfiguration and of such a dimension as to be co-extensive with theperimetral surfaces of the molded blocks 24 and 38, when assembled, arepositioned in stacked relationship on the upper and lower surfaces ofthe blocks 24 and 38 respectively. Each of the plastic members or wafers50, between which contact blades such as 54 and 60 are positioned ashereinafter described, have tubular projections 51 which lit intocounter-bored recesses of adjoining wafers or beds 50 when stacked inproper position. Nested and stacked against the outer-most insulatorwafers or beds 50 are insulator wafers or beds 52, each of which hastubular projections for nesting in the counter-bored tubular projectionsof its adjacent bed 50. The members 52 have a rectangular recess in oneface for receiving a rectangular plate 53. A set of elongate rivets 49are inserted through suitable openings in the plate 53 and the elongatecylindrical bores formed by the counter bored tubular projections of themembers 52, beds 50, and plastic blocks 24 and 38 to clamp the assemblytogether, and thus complete the assembly of the fixed end of the relay.The spring plate 53 accommodates thermal expansion and contraction whilemaintaining tightness of the assembly.

Each of the molded plastic beds 50 is contigurated to retain a pluralityof the elongate metallic contact blades 54 or 6@ stamped from flat sheetstock of suitable thickness and after conventional contact elements suchas 59 are fastened thereto, they are ready for assembly without thenecessity of forming or pretensioning. In the illustrated embodiment ofthe invention each of the wafers or beds has shallow recesses or slotsfor holding three of the contact blades, such as 54 or 60. Each of theslots has a side wall 55 against which the Contact blades 54 or 66engage when in the proper precise alignment. An integral projection 56,extending into the slot from each of the side walls 55, ts in a notch inthe edge of each of the Contact blades 54 to insure that the contactblades are in their proper longitudinal position. The side wall oppositeto side wall 55 of each of the slots is provided with an integrallyformed finger 57 which normally extends resiliently into the slot, butwhen a contact blade such as 54 is positioned therein, the linger orprojection 57 is urged out of the slot to engage against the edge of thecontact blade 54. The force of the finger 57 not only holds the contactblades in intimate engagement with its respective wall 55 for properprecise alignment, but also prevents the inserted contact blade fromdropping out of its respective slot or recess while the various platesare being stacked on top of one another and on the blocks 24 and 38during assembly. By present manufacturing techniques, these criticalsurfaces of the insulating members 50 can be made parallel to each otherwith a high degree of accuracy, and, by means of the resilient fingers57, the various contact blades are easily assembled in precise parallelalignment with zero tolerance.

Each of the contact blades 54 and 60 are provided with projections 59which are formed during stamping and embed in the respective recesses ofthe wafers 50 so that when the iixed end of the relay is assembled, theblades 54 and 60 are fixed in precise alignment against external forces.

It will be noted that the working or left-hand end of the contact blades60, as viewed in FIG. 2, each have a longitudinally extending flatfinger or projection 61 (FIG. l) which has a laterally extending hookportion 62; and during assembly an insulating bed 50 carrying thecontact blades is interposed between those carrying the contact blades54.

The working or front end of the relay assembly includes a molded member63, which may be made of the same insulating material, as the fixed endof the relay.

The member 63 is substantially a rectangular frame that is open at thefront and back and has integral partitions arranged to form a grate-likestructure. The frame 63 has a generally rectangular central opening 64,the upper wall of which is comprised of an integral partition 65 and thelower wall of which is comprised of an integral partition 66. Parallelto and spaced between the top perimetral wall of the member 63 and theintegral partition 65 are a pair of narrow parallel partitions or crossmembers 68 and 69. Also, parallel to and spaced between a partiti-on 7@and the bottom perimetral wall of the member 63 are a pair of spacednarrow parallel partitions or cross members 71 and 72. Verticallyextending spaced integral partitions 73 connect partitions 65 and 70 tothe top and bottom of the member 63 respectively and to the narrowpartitions 68, 69, 71 and 72 to complete the gratelike structure so asto provide a plurality of rectangular openings both above and below thecore 10, through which the contact blades extend. These verticalpartitions provide strength and rigidity to the member 63, particularlythe narrow partitions 64, 69, 71 and 72.

The member 63 is mounted on the left hand or working end of the core 10by inserting the core 10 and the free end of the armature 16 through thecentral opening 64 until rectangular notches 73 (FIG. 3) in oppositeside edges of the core 1G are in registry with rectangular abutments orshoulders 74 integrally formed in the side walls of the opening 64. Thefree ends of the contact blades 54 and 60 are guided into respectiveopenings such as formed by the narrow cross members 68 and 69, and thecross members 71 and 72. The core 10 and member 63 are then shiftedrelative to one another so that the core 10 engages at its under surfaceinwardly extending ridges 75 formed integrally with the side walls ofthe opening 64 fore and aft of the shoulder 74 and extendingcoextensively with the depth of the side walls of the memer 63. Theridges 75 are accurately molded so that their upper surface when engagedby the bottom surface of the core 10 precisely position the core 10relative to the member 63. To fasten the member 63 to the core 10, anarcuate spring 76 is forced into the rectangular opening 64 in the spacebetween the upper surface of the core 10 and the partition 65 with theedges of the spring 76 engaging ridges 77 integrally formed adjacent thetop of the opening 64. The force of the spring 76 secures the member 63.The member 63 is held in precise longitudinal position by the abutments74 in the notches 73 of the core as aforementioned. When the member 63is so positioned, spools 14 carrying the coil windings 15 are confinedin precise position on the central portion of the core 16 between rearedge 80 of the block 63 and the forward surface of blocks 24 and 38 atthe fixed end of the relay.

The offset portion 18 of the armature 16 engages the upper surface 81 ofthe partition 66 to register accurately the dropped away or releasedposition of the relay armature.

Referring to FIG. 2, a low rate coil spring 82 is compressed, duringassembly, between a spring seat 83 on surface 84 of the partition 65 ofthe molded member 63 and a spring seat 85 mounted in an opening in theoffset portion of the relay armature 16. This spring 82 is provided forcontinually biasing the armature 16 toward its released position whereinits underside rests firmly on the surface 8l, of the molded member 63.

When the molded member 63 is positioned on the core 10 as described, theworking ends of the front contact blades 54 are positioned in therespective openings between the top of the member 63 and the narrowpartition 68, and also are positioned in the openings below the core 10between the partition 'l0 and the partition 71. The back contact blades54 are positioned in the openings between the narrow partition 69 andthe partition 65 above the core 10, and the partition 72 and the bottomof the member 63, respectively below the core 10. The so-called movablecontact blades 60 are positioned between the partitions 68 and 69 andthe partitions 71 and 72, respectively.

The upper surfaces of the partitions 68 and 71 respectively are engagedby the front contact blades 54 to accurately register their released orunengaged position. Back contact arms 54 engage the undersurface of thepartitions 69 and 72 when released to accurately register their releasedpositions. To minimize manufacturing variations, the surfaces of themolded block 63 which register the position of the relay parts, such asthe core 10, the contact blades 54, and the armature 16 are arranged forthe least accumulation of tolerances and to negate the variation inthickness of parts where possible.

Specifically, the distance between the upper surface of the shoulders 75and the upper surface of the partition 66 determines the open air gap ofthe relay without regard to variations in thickness of the core 10 orthe partition 66. Only a variation in the thickness of the portion 18 ofthe armature 16 would affect the dimensions of the open air gap and thetravel of the armature. However, even if there were slight variations inthis thickness the operating characteristics of the relay are notadversely affected as is described hereinafter. Also, as long as theupper surface of the cross members 68 and 71, and

,the lower surface of the cross members 69 and 72 are 9` preciselypositioned from the upper surface of the shoulder 75, the upper surfaceof the portion 66 and from each other, the thickness of the crossmembers 68, 69, 71 and 72 may vary without aiecting the intendedoperation yof the relay.

In the preferred embodiment illustrated in FIGS. 1 through 3, coilsprings such as 86 and 87 are inserted in the frame 63 to constantlyurge front and back contact blades 54 respectively toward their releasedposition. Springs 86 are inserted between each of the front contacts 54and the top wall of the frame 63 and the partition 70 respectively.Springs 87 are inserted between each of the back contacts 54 and thebottom wall of the frame 63 and the partition 65 respectively. Circularprojections or spring seats are formed integral with the inner face ofthe top and bottom of the frame 63 and the upper and lower surfaces ofthe partitions 65 and 70 and on the front and back contact blades 54 sothat the springs 86 and 87 are secured close to the base of each bifur-Acated portion of the contact blades 54. The bifurcation is provided toinsure reliability of contact. These coil springs 86 and 87 which havelow spring constants, Iare of such a length that they are compressed aconsiderable distance when inserted in position so that the desiredloading pressures are continually being exerted against the blades 544and 60. Thus, the exerted spring pressures remain substantiallyconstant over their entire operating range because the amount of springdellection, during relay operation, is small compared to the springdeection when assembled. Therefore, there is no need for relayadjustment after -assembly to obtain the desired loading or contactpressures. Also, there is no need for adjustment to maintain the desiredloading or contact pressures, if the silver contacts elements 50 havebecome Worn because of continued operation.

To illustrate the relatively uniform contact and loading pressure overthe total operating distance of the armature, reference is -made to FIG.l5. It is known that the elongation or compression, in the deformationof an elastic body is proportional to the force per unit area. Thus, ifthe amount of force F of a spring is equal to a constant K times theamount of the deflection of the spring D, and the constant is low, thepressure exerted by the spring will increase as illustrated by line 99of the graph of FIG. l5 as the spring is compressed or deflected overits entire range from point C on the graph of FIG. to point D. However,in accord-ance with the present invention, the springs 86 and 87 arecompressed a distance Which may be represented from the point C to pointE when the contact blades 54 are in their released position. Therefore,during the operation of the relay the amount of further spr-ingdeflection or compression is only that which occurs between the points Eand E. Thus, it is apparent that the force F varies only slightly duringthe entire travel of the contacts. This is represented by the slightvariation in force accuracy between the arrows designated lat I. Inactual practice, a spring such as 86 and 87 is compressed approximatey90% of its total movement or compression when inserted and its operatingrange is approximately 5%. When compressed as above, in one practicalapplication, the spring exerts substantially grams of pressure on thefront and back contacts 54 over their entire range of travel. Spring 82for biasing the armature is suitably selected to have similarcharacteristics.

As shown in FIGS. 1 through 3, the movable contact blades 60 by theirprojections 61 t in slits of a movable card 90, made of suitableinsulating material, carried on the extend-ing left-hand end of thearmature 16. The movable card 90 is mounted on the larmature 16, and, inproper engagement with movable contact blades 60, by rst sliding themovable card 90 over the projection 61 of the movable contact blades 60and the projecting end of the armature 16 and then, displacing themovable card 90 to the right, as viewed in FIG. 1, so that the movablecard slides into slots formed by the hook portion 62 of the projection61 (see FIG. 3) provided in the left-hand ends of the movable contactblades 60. This card 90 is then held firmly in its assembled position bya resilient projection or linger 92 on card 90 which finger engages ahole 93 in the larmature 16 when the card 90 is properly positioned.This movable card 90 is also provided with protruding pockets 94 (seeFIGS. l and 2) for receiving a relay identification card (not shown).

As shown in the accompanying drawings, with the windings 15 deenergized,the relay armature 16 is maintained in its normal released position (asillustrated) by coil spring 82 which although larger than the springs 86and 87, but compressed to have similar characteristics, continuallyexerts its predetermined spring pressure down- Wardly on the armature 16and thereby biases the armature 16 against the upper surface 81 of thepartition 66 of the front molded block 63. In this position, the movablecard 90 is in its lowermost operating position and thereby causesmovable contact blades 66 to engage back contact blades 54, moving theseback contact blades 54 away from their unengaged positions Ias delinedby the lower surfaces of partitions 69 and 72. In this operationposition, coil springs 87 provide .the desired contact pressurenecessary to insure good electrical contact between the movable contactarms 60` and the back contact blades 54, and furthermore, in conjunctionwith coil spring 82 provides the desired armature loading pressure,while the armature 16 is in its released position. Referring to FIG. 2it will be noted that with the armature 16 thus released, front contactarms 54 are held rmly in their unengaged position; i.e. against theassociated upper surfaces of partitions 68 and 71 of front molded block63, by low rate coil springs 86.

If the rel-ay windings 15 are now energized, armature 16 is attractedtoward the underside of the relay core 10, by the resulting magneticilux flowing through the series magnetic circuit formed by core 10 andarmature 16. From the description already set forth, -it should beobvious that the travel of armature 16 has been accurately set byregistering the desired armature release position (surface 81 of thepartition 66 of the molded block 63), and the position of the left-handend of the relay core 10 (ridge 75 in the central opening 64 of thefront molded block 63). Furthermore, and with reference to theaccompanying drawings, it will be noted that the working air gap of therelay has a relatively large crosssectional area as compared to thelength of the air gap, thus preventing any relatively rapid changes ofthe magnetic pull on the relay armature 16 during energization of thewindings 15 (see pull curve 110 of FIG. 14 hereinafter described).

The movable card 90 now carries movable contact blades 60 in an upwardlydirection to break the contact between the movable contact blades 60 andthe back contact blades 54, and then make contact between the movablecontact blades 60 and the front contact blades 54. It will be noted,from the accompanying drawings and the description previously set forth,that until back contact blades 54 engage the underside of partition-s 69and 72 respectively in the front molded block 63, a good electricalcontact is maintained between the movable contact -arms 60 and the backcontact blades 54 by the individual coil springs 87.

As soon as front contact blades 54 are engaged by movable contact blades60, they will be lifted off the upper side or surface of partitions 68and 71 of the front molded block 63 'and tend to further compress theassociated coil springs 86. The pressure of the springs 86 isimmediately effective to insure proper electrical contact betweenmovable contactarme 60 and front contact arms 54. In addition, forreasons previously set forth, the exerted spring pressure of coilsprings 86 remains substantially at the pressure preset by compressingthem during assembly.

Referring to FIG. 2, a thin, accurately dimensioned sheet or plate 96 ofsuitable nonmagnetic material is attached to the upper side of theleft-hand end 18 of the relay armature 16 and covers the working air gapof the relay. This plate 96 is provided to prevent the armature 16 frombeing stuck in its attracted position by any residual magnetism presentin the relay magnetic structure, after the relay windings have beendeenergized, to release the armature 16. The sheet 96 is retained inposition by the spring seat which is rectangular in crosssection vand tsthrough a corresponding rectangular hole in the sheet 96. The plate 96and the spring seat S5 are held by the pressure of the spring 82.

If the relay windings 15 are now deenergized, the combined loadingpressures exerted by coil springs 86 and the coil spring 82 until frontcontacts 54 are disengaged are effective to cause the armature 16 toreturn to its normal released position, as shown, wherein it rests onsur'- face 81 of the front molded frame 63, and wherein mov* ablecontact blades are brought into engagement with back contact blades 54.

Referring to the diagram of FIG. 14, line represents the distance oftravel of the portion 18 of the relay armature 16. Line 101 representsforce. The solid line, generally referred to at 102 represents the loadon the relay armature during its travel from the fully released positionto the closed position. When the armature is fully released, thearmature load is as represented at portion 103 of the solid line of 102.During travel of the armature 16 between points 103 and 1194 of line102, the biasing force of the spring 82 which is decreased by thepressure of the springs 87 provides a load which remains substantiallyconstant as is apparent from the slight slope of this portion of line102. When the back contacts 54 open, the load on the armature increasesabruptly to point 105 on the line 162 because the springs 87 no longeract to reduce the load. Between points 1115 and 106, the load remainssubstantially constant because of the low spring constant and theposition of the spring 82 in substantial alignment with the air gap.When the front contacts 54 close, the armature load increases abruptlyas represented by point 107 on line 102. This load remains substantiallyconstant for the remainder of the armature travel because of theposition and low spring constants of the springs 86 with the spring 82now aiding the springs 86 in loading the armature. Thus, if because ofmanufacturing variations the travel of the armature is reduced slightlyso that it is fully released at point 108 on the line 100, for example,the load on the armature remains substantially the same. Also eventhough the Contact elements 59 wear down after long and continued used,which would cause earlier disengagement with back contacts 54, and laterengagement with front contacts 54, the loading pressure caused by thesecontacts 54, and the contact pressure remains practically the same.Solid line 110 of FIG. 14 represents the pull of the armature from itsfull released position to its fully picked up position. As seen fromthis diagram the slope of the pull curve 11@ is gradual which permits ofa substantially wide variation in voltage range to effect the sameoperating characteristics and render the relay relatively insensitive toany small production variation.

The coil springs 82, 86 and 87 are all mounted in substantially verticalalignment with the working airgap of the relay close to the contactelements 59 and thus, the various predetermined pressures exerted bythese coil springs accurately determine the loading pressures on therelay armature 16, and therefore also, the operating values of the relayas pointed out in connection with FIG. 14. It is apparent that the coilsprings 82, S6 and 87 are removably mounted in the relay structure, sothat different value coil springs may be inserted, for example, if it isdesired to change the operating values of the relay, as is sometimesnecessary if similar relays are to be utilized in more than one type ofcircuit arrangement.

In actual practice, it has been determined that a relay according to thepresent invention reliably operates solid state devices. This isbelieved primarily due to the relatively constant contact pressure overa generous compression distance. The initial contact is close to itsselected Contact pressure and is relatively uniform throughout theentire range of contact travel. The short distance between the springs8d, 87 and the contact 59 causes it to come up fast. Thus, there appearsto be no contact bounce until after the armature and contacts have completed their travel, and the time for operating the solid state devicesis sutiicient during the interim while the movable contacts are inengagement with the iixed contacts during armature travel.

Referring to FIG. 10, an alternative embodiment is illustrated whereinthe contact blades referred to at 54 may be made to have integrallateral projections bent to form a at spring to provide the desiredcontact pressure. The flat spring 11S may be compressed sufficiently toprovide characteristics similar to the coil springs 86 and S7 of thepreviously described embodiment.

FIG. 1l illustrates a further modification wherein liat springs such as116 may be inserted in position in place of the coil springs 86 and 87.FIG. 12 illustrates a still further modiiication whereby a coil spring117 may be insulatedly connected at one end to a plastic member 12)positioned in an opening of a front contact blade 54 and at its oppositeend to a similar member 120 positioned in an opening of a back contactblade 54. The spring would be under sutlicient tension to provide therequired loading pressure as described in the previous embodiments.

A relay constructed in accordane with the present invention is providedwith two energizing coils 15, each of which is capable of operating therelay armature independently. Each of the windings 15 has a resistancein the order of 180 ohms and is adapted to be operated in the 12 to 30volt range. Referring to the graph of FIG. 13, which represents the B/Hcurve of the relay, line represents the amount of magnetizing force inampere turns H(NI) required to produce B kilo-lines per square inch ofthe flux density. It is apparent from FIG. 13 that when the armature isclosed the magnetic circuit is saturated at approximately one hundredten kilo-lines per square inch and the slope of line 125 is gradual fromapproximately three hundred ampere turns onward. The knee of the curveof line 125 commences at approximately one hundred ampere turns. Theopen air gap curve represented by line 126 illustrates that saturationoccurs at slightly less tlux density than the closed air gap curve. Therelay of the present invention picks up at point 127 on the curve 126which is substantially in the saturation range of the curve 125. Oncepicked up the relay will stay up with a ux density as low asapproximately eighty kilo-lines per square inch of force which isrepresented by point 128 on line 125. The armature drops away at point130 which is approximately sixty kilo-lines per square inch. Because therelay operates in the area of saturation the ampere turns or force canvary considerably without causing an appreciable change in the uxdensity, and thus the pull on the armature. This, together with thelarge air gap area provides a flat pull curve that is insensitive torelatively minor voltage variations.

Having thus described a relay according to the invention with severalmodifications of the contact spring arrangement, it is understood thatother modifications, particularly as regards the shapes of the componentparts, as well as the arrangement of the Contact blades, may be madewithout departing from the spirit or scope of the present invention.

What I claim is:

1. A relay comprising, an elongated core substantially rectangular incross-section,

(a) an energizable coil assembly mounted on said core and positioned tohave a forward portion of the core extend outwardly of the coil;

(b) an armature hingedly connected adjacent one end of the core anddisposed to have a forward portion of the armature attracted to theforward portion of the core upon energization of the coil;

(c) a frame of insulative material on the forward portion of the corehaving an internal dimension to receive the forward portions of the coreand armature;

(d) said frame having inwardly extending integrally formed shoulders inengagement with the core to position precisely the frame on the core;

(e) means engaging the forward portion of the core and the frame tosecure the frame in the precise position;

(f) said frame having a first integral cross member extending spacedfrom the core and engageable by the forward portion of the armature whenthe coil is deenergized to precisely x the travel of the armature;

(g) a plurality of movable contact blades insulatively attached adjacentsaid one end of the core and positioned to extend through the frame;

(h) an insulative card afixed to the armature and the opposite ends ofsaid movable contact blades to precisely positionthe extending oppositeends of said movable contact blades relative to the armature;

(i) a plurality of fixed contact blades insulatively attached at saidone end of the core and extending in vertical spaced alignment from themovable contact blades through said frame to be engaged and disengagedat their opposite ends by their associated movable blades in accordancewith the operation of the armature;

(j) said frame also having other integral cross members each having asurface opposing that portion of each respective fixed contact blade inthe frame and so positioned to limit the position of each fixed contactblade when disengaged by its aligned movable contact blade; and

(k) spring means positioned in the frame disposed to engage a portion ofeach fixed contact blade in aligned spaced relation to the forwardportion of the core constantly urging each fixed contact blade towardsaid opposing surface of its respective cross member.

2. A relay as claimed in claim 1 wherein the forward portion of the corehas a pair of recesses formed in opposite edges thereof and theintegrally formed shoulders each have an integral extending portion tomate in the recesses when the core engages the shoulders of the frame.

3. A relay as claimed in claim 1 wherein the frame has an integrallyformed interior surface spaced from the surface of the forward portionof the core opposite the armature and the means for securing the framein precise position is an arcuate spring means positionally insertedwhen compressed between the forward portion of the core and the spacedinterior surface.

4. An electromagnetic relay, comprising (a) a rectilinear magnetic coresubstantially rectangular `in cross section and having adjacent its rearend an irregular opening defined at its forward edge by a transversewall;

(b) a coil `structure including a spool having a central rectangularopening positioned on said core with opposite ends of the core extendingaxially outwardly through the central opening;

(c) an armature rectangular in cross section and having adjacent one endat its side edges a pair of oppositely positioned notches having alength greater than the thickness of the core and of lsuch a depth thatthe distance between the inner edges of the notches is less than thelength of the transverse wall at the forward edge of the irregular coreopening;

(d) said armature being positioned in the irregular 14 core opening withthe side of the core mating with the notches of the armature;

(e) the opposite end of the armature extending toward and beyond theforward end of the core;

(f) a pair of mating insulating members positioned on opposite sides ofthe core and having a portion extending into the irregular openingrearwardly of the armature;

(g) resilient means mounted intermediate its upper and lower surfaces inthe front portion of the mated insulating members urging constantly thearmature in contact with an edge of the transverse wall of saidirregular opening;

(h) a plurality of insulative beds so congurated to mate with the upperand lower surfaces of the mated insulating members and with each otherpositioned in stacked relationship on the upper and lower surfaces ofthe insulating members;

(i) a plurality of elongated metallic contact blades positioned inprecise alignment and fixed at one end between the stacked insulativebeds;

(j) a molded grate-like structure attached to the extending forward endof the core with the free ends of the contact blades and the armatureextending forwardly thereof through suitable openings provided therefor,

(k) first spring means mounted in the grate-like structure constantlyurging the armature against an associated surface of the structure,

(l) second spring means mounted in the grate-like structure constantlyurging certain of the contact blades against associated surfaces of thestructure, and

(m) a card afiixed to the extending end of the armature and to others ofthe contact blades to cause such other contact blades to engage saidcertain contact blades when the coil windings are energized.

5. An electromagnetic relay as specified in claim 4 wherein said firstand second spring means are coil springs which are removably mountedbetween the surfaces in said grate-like structure and said armature andsaid certain contact blades.

=6. An electromagnetic relay, comprising (a) a magnetic core;

(b) an energizing winding on said core;

(c) a back insulator member aflixed to one end of said core;

(d) an armature pivotally mounted on this end of said core and extendingtoward but spaced bya Working air gap from the opposite extending end ofsaid core;

(e) said armature being attracted to or released from said core inaccordance with the energization of said winding;

(f) a movable card mounted on the extending end of said armature;

(g) a plurality of contact blades each having one end fixed by said backinsulator member and certain of which have their extending ends carriedby said movable card to selectively engage the extending ends of thosecontact blades not carried by said movable card in accordance with theoperating position of said armature;

(h) a front insulator member having registered surface means therein forrespectively determining the position of the extending end of said coreand the unengaged positions of the extending ends of those contactblades not carried by said movable card;

(i) first spring means operatively positioned in the 7. Anelectromagnetic relay as claimed in claim 6 wherein said back insulatormember has a plurality of Contact slots formed therein for receiving oneend of each of said plurality of contact blades, each of said contactslots having at least one surface thereof accurately registered to beparallel to a corresponding surface of the remaining contact slots, andsaid back insulator member including integral resilient projections forbiasingV said contact blades against said accurately registered surfacesof said Contact slots when the contact blade-s are positioned therein.

S. An electromagnetic relay as claimed in claim 6 wherein said first andsecond spring means are positioned in substantial alignment with theWorking air gap of the relay rearwardly of the card.

9. An electromagnetic relay as claimed in claim 6 wherein said iirst andsecond spring means are low rate coil springs.

10. An electromagnetic relay as claimed in claim 6 wherein said secondspring means for biasing the contact blades are low rate flat springs.

11. A relay as claimed in claim 6 wherein said front insulator memberincludes a further registered surface means therein for determining thereleased position of said armature, and wherein said iirst and secondspring means are coil springs in a compressed condition respectivelypositioned to engage said armature and the respective Contact blades notcarried by the card, and said coil springs also engaging the spacedopposing surfaces of the front insulator member.

i2. A relay as claimed in claim 6 wherein said contact blades notcarried by the card are positioned in spaced alignment, and the secondspring means for biasing the aligned contact blades is a coil springinsulatively connected at opposite ends under tension between saidaligned contact blades.

13. rThe relay according to claim 6 wherein the amount of deection ofsaid first and second spring means in placing them in their assembledpositions is relatively large compared to the amount of deflection ofsaid iirst and second spring means during operation of said armature.

14. In a relay,

(a) a core having a cut out portion at one end thereof forming atransverse edge in said core spaced from said one end of said core,

(b) an armature mounted in said cut out portion to pivot about an axissubstantially parallel to said transverse edge and extending toward butspaced by a working air gap from the opposite end of said core,

(c) an insulative member positioned and formed to iixedly engage saidone end of said ocre and having a portion extending into said cut outportion of said core to retain said armature in operative position; and

(d) resilient means mounted between said armature and said insulatormember to constantly urge said armature into engagement with thetransverse edge of the core.

l5. In a relay,

(a) an armature operatively mounted at one end with .its free extendingend movable to opposite limit positions, said armature having a holetherein adjacent its free extending end,

(b) a plurality of contact blades each having one end -xed and the otherend extending substantially parallel with said armature, certain of saidcontact blades being movable to selectively engage others of saidcontact blades in accordance with the position of said armature, each ofsaid movable contact blades having a transverse slot therein adjacentits extending end, and

(c) a card of insulation having openings therein to receive ttingly theextending end of said armature and the extending ends of said movableContact blades and having a resilient integral hooked projection tetherein normally projecting yieldingly into that opening which receivessaid armature and positioned to engage in said hole in said armaturewhen said card is fitted into said transverse slots in said movableContact blades.

16. An article of manufacture adapted to be secured to the core of .arelay for precisely positioning the release position of the armature andthe fixed contact blades of the relay, comprising,

(a) a molded frame of insulative material of suflicient internal lateraldimension to receive a relay core; (b) a pair of integrally formedoppositely disposed shoulders in the interior of the frame to be engagedby the relay core to position the frame precisely relative to the core;

(c) a first integrally formed member, one surface of which is preciselypositioned from said shoulders and disposed to be engaged by thearmature in its released position; and

(d) a plurality of second integrally formed members, each having onesurface precisely positioned from said shoulders and from each otheragainst which the fixed contact blades of the relay engage whenreleased.

17. In a relay structure,

(a) a plurality of fixed and movable contact blades each insulatedlysupported at one end, and the fixed contact blades of which have theirfree ends relatively located for engagement by saidv movable Contactblades whose free ends are moved in accordance with the operation of arelay armature,

(b) a frame having a plurality of registering surface means to determinethe unengaged positions of the free ends of said xed contact blades andother surface means disposed opposing said registering surface means andspaced therefrom by a predetermined distance,

(c) spring means located between each of said opposing surfaces meansand an associated one of said fixed contact blades for continuallyurging that contact blade toward its registering surface means,

(d) said spring means having a normal non-deflected length greatly inexcess of said predetermined distance between said registering surfacemeans and said opposing surface means in said frame,

(e) whereby the amount of detiection of said spring means by itslocation is much greater than the amount of deliection of said springmeans during relay operation, and

(f) whereby said spring means exerts a substantially constant biasingforce on the associated fixed contact blade during operation of theassociated movable Contact blade and regardless of contact wear duringsuch operations.

18. An electromagnetic relay comprising,

(a) a generally flat rectangular core having notches at both sidesthereof adjacent one end,

(b) a front insulator block having shoulders thereon to mate with thenotches on said core,

(c) first resilient means compressibly mounted between said core and anopposing surface on said insulator member for continuously biasing saidcore against said shoulders in assembled position,

(d) said core having a cut out portion at its opposite end to form atransverse edge in said core spaced from said opposite end,

(e) an armature mounted in said cut out portion to pivot about saidtransverse edge,

(f) a back insulator block fixedly mounted on the cut out end of saidcore and having an extending portion which extends into the cut outportion of said core to retain said armature in assembled positionWithin said cut out portion,

g) an energizing winding interposed on said core be- .tween said frontand back insulator blocks.

(h) second resilient means compressibly mounted between said armatureand the extending portion of said back insulator block for continuouslybiasing said armature against the transverse pivoting edge of said core,

(i) a plurality of insulator members mounted in stacked relationship onsaid back insulator block and carrying a plurality of contact fingerswhich extend through openings in the front insulator block,

(j) anchoring means for holding the back insulator block and saidinsulator members in stacked relationship,

(k) a card carried on the extending end of said armature and effectiveto carry certain of said contact -iingers into engagement with theothers of said contact fingers not carried by said card,

(l) a plurality of surfaces on said front insulator block formed to xthe released position of said armature and the respective unengagedpositions of those contact ngers not carried by said card,

(m) third resilient means compressibly mounted between said armature andan opposing surface of said front insulator block to constantly biassaid armature toward its released position, and

(n) fourth resilient means compressibly mounted between those contactfingers not carried by said card and opposing surfaces on said frontinsulator block to constantly bias those contact ngers not carried bysaid card toward their respective unengaged posi- 5 tions.

References Cited bythe Examiner UNITED STATES PATENTS ROBERT K.SCHAEFER, Acting Primary Examiner.

25 BERNARD A. GILHEANY, Examiner.

1. A REALY COMPRISING, AN ELONGATED CORE SUBSTANTIALLY RECTANGULAR INCROSS-SECTION (A) AN ENERGIZABLE COIL ASSEMBLY MOUNTED ON SAID CORE ANDPOSITION TO HAVE A FORWARD PORTION OF THE CORE EXTEND OUTWARDLY OF THECOIL; (B) AN ARMATURE HINGEDLY CONNECTED ADJACENT ONE END OF THE COREAND DISPOSED TO HAVE A FORWARD PORTION OF THE ARMATURE ATTRACTED TO THEFORWARD PORTION OF THE CORE UPON ENERGIZATION OF THE COIL; (C) A FRAMEOF INSULATIVE MATERIAL ON THE FORWARD PORTION OF THE CORE HAVING ANINTERNAL DIMENSION TO RECEIVE THE FORWARD PORTION OF THE CORE ANDARMATURE; (D) SAID FRAME HAVING INWARDLY EXTENDING INTEGRALLY FORMEDSHOULDERS IN ENGAGEMENT WITH THE CORE TO POSITION PRECISELY THE FRAME ONTHE CORE; (E) M EANS ENGAGING THE FORWARD PORTION OIF THE CORE AND THEFRAME TO SECURE THE FRAME IN THE PRECISE POSITION; (F) SAID FRAME HAVINGA FIRST INTEGRAL CROSS MEMBER EXTENDING SPACED FROM THE CORE ANDENGAGEBLE THE THE FORWARD PORTION OF THE ARMATURE WHEN THE COIL ISDEENERGIZED TO PRECISELY FIX THE TRAVEL OF THE ARMATURE; (G) A PLURALITYOF MOVALBE CONTACT BLADES INSULATIVELY ATTACHED ADJACENT SAID ONE END OFTHE CORE AND POSITIONED TO EXTEND THROUGH THE FRAME; (H) AN INSULATIVECARD AFFIXED TO THE ARMATURE AND THE OPPOSIT ENDS OF SAID MOVABLECONTACT BLADES TO PRECISELY POSITION THE EXTENDING OPPOSITE ENDS OF SAIDMOVABLE CONTACT BLADES RELATIVE TO THE ARMATURE; (I) A PLURALITY OFFIXED CONTACT BLADES INSULATIVELY ATTACHED AT SAID ONE END OF THE COREAND EXTENDING IN VERTICAL SPACED ALIGNMENT FROM THE MOVABLE CONTACTBLADES THROUGH SAID FRAME TO BE ENGAGED AND DISENGAGED AT THEIR OPPOSITEENDS BY THEIR ASSOCIATE MOVABLE BLADES IN ACCORDANCE WITH THE OPERATIONTION OF THE ARMATURE; (J) SAID FRAME ALSO HAVING OTHER INTEGRAL CROSSMEMBERS EACH HAVING A SURFACE OPPOSITE THAT PORTION OF EACH RESPECTIVEFIXED CONTACT BLADE IN THE SO POSITIONED TO LIMIT THE POSITION OF EACHFIXED CONTACT BLADE WHEN DISENGAGED BY ITS ALIGNED MOVABLE CONTACTBLADE; AND (K) SPRING MEANS POSITION IN THE FRAME DISPOSED TO ENGAGE APORTION OF EACH FIXED CONTACT BLADE IN ALIGNED SPACED RELATION TO THEFORWARD PORTION OF THE CORE CONSTANTLY URGING EACH FIXED CONTACT BLADETOWARD SAID OPPOSITE SURFACT OF ITS RESPECTIVE CROSS MEMBER.